December 6, 2007 IBM scientists have announced a breakthrough that could lead to a new generation of supercomputers that squeeze the processing power of today's giants into the form factor of a laptop. The research is based on the use of a light pulses sent through silicon instead of electrical signals on wires which make up conventional computer chips and also promises incredibly energy efficient processors that would expend only the energy of a light bulb to achieve what current supercomputers do with enough power to run hundreds of homes.

The paper, published in the journal Optics Express, concerns the silicon Mach-Zehnder electro-optic modulator - a device which converts electrical signals into pulses of light and promises to significantly reduce cost, energy and heat while increasing communications bandwidth between the cores by a factor of more than 100 over wired chips. The new modulator, which according to IBM is 100 to 1,000 times smaller in size compared to previously demonstrated devices of its kind, acts as a very fast “shutter” to modulate the intensity of the input laser beam and converts a stream of digital bits (“1”s and “0”s) from electrical signals into light pulses.

“Work is underway within IBM and in the industry to pack many more computing cores on a single chip, but today’s on-chip communications technology would overheat and be far too slow to handle that increase in workload,” said Dr. T.C. Chen, vice president, Science and Technology, IBM Research. “What we have done is a significant step toward building a vastly smaller and more power-efficient way to connect those cores, in a way that nobody has done before.”

IBM explain the potential of the technology in terms of the current processor which powers the Sony Playstation 3 - while this contains nine cores on a single chip, the new technology aims to connect hundreds or thousands of cores together on a tiny chip by eliminating the wires required to connect them.

“We believe this is a major advancement in the field of on-chip silicon nanophotonics,” said Dr. Will Green, the lead IBM scientist on the project. “Just like fiber optic networks have enabled the rapid expansion of the Internet by enabling users to exchange huge amounts of data from anywhere in the world, IBM’s technology is bringing similar capabilities to the computer chip.”

The report on this work, entitled “Ultra-compact, low RF power, 10 Gb/s silicon Mach-Zehnder modulator” by William M. J. Green, Michael J. Rooks, Lidija Sekaric, and Yurii A. Vlasov of IBM’s T.J.WatsonResearch Center in Yorktown Heights, N.Y. is published in Volume 15 of the journal Optics Express and was supported by the Defense Advanced Research Projects Agency (DARPA) through the Defense Sciences Office program “Slowing, Storing and Processing Light”.